Why Convert Kilocalories to Kilojoules?
Converting between kilocalories (kcal) and kilojoules (kJ) is one of the most common energy conversions. Whether for engineering, cooking, travel, or science, knowing how to quickly convert kcal to kJ saves time and prevents errors.
Energy conversions between kcal and kJ are important for nutrition, electricity costs, and engineering. Food labels in different countries use different energy units — China and the EU use kilojoules (kJ), while the US and Australia use Calories (kcal). Understanding kWh-to-joule conversions helps calculate electricity costs and compare energy efficiency of appliances. In HVAC, BTU ratings are standard in North America while watts or kilowatts are used elsewhere.
How to Convert Kilocalories to Kilojoules
To convert kilocalories to kilojoules, use the following formula:
kJ = kcal × 4.184
Example: 1 kcal = 4.184 kJ
For example, 5 kcal = 20.92 kJ, 10 kcal = 41.84 kJ, and 100 kcal = 418.4 kJ. Our calculator above performs this conversion instantly with full precision — no rounding errors.
Common Use Cases
- Daily calorie intake for an average adult: 2000 kcal = 8368 kJ
- A bowl of cooked white rice: 200 kcal = 836.8 kJ
- Energy burned in 30 minutes of running: 300 kcal = 1255.2 kJ
- A Big Mac hamburger: 550 kcal = 2301.2 kJ
- A medium-sized banana: 100 kcal = 418.4 kJ
Common Mistakes to Avoid
- Calorie vs kilocalorie: Food labels in the US show "Calories" (capital C) which are actually kilocalories (kcal). 1 food Calorie = 1 kcal = 4.184 kJ.
- kWh is not kW: Kilowatt-hours (kWh) measure energy consumed over time, while kilowatts (kW) measure instantaneous power. Don't confuse them.
- Regional food labels: China/EU labels use kilojoules (kJ), US/Australia use Calories (kcal). Check which system before comparing.
Pro Tips
- Memorize the factor: 1 kcal = 4.184 kJ. For quick mental math, remember this base conversion.
- Quick reference: 5 kcal = 20.92 kJ · 10 kcal = 41.84 kJ · 25 kcal = 104.6 kJ · 50 kcal = 209.2 kJ · 100 kcal = 418.4 kJ
- Bookmark this page: Save this converter for instant access. It works offline once loaded — no internet needed.
Kilocalories to Kilojoules Conversion Table
| kcal | kJ |
|---|---|
| 0.01 kcal | 0.04184 kJ |
| 0.1 kcal | 0.4184 kJ |
| 0.5 kcal | 2.092 kJ |
| 1 kcal | 4.184 kJ |
| 2 kcal | 8.368 kJ |
| 5 kcal | 20.92 kJ |
| 10 kcal | 41.84 kJ |
| 20 kcal | 83.68 kJ |
| 50 kcal | 209.2 kJ |
| 100 kcal | 418.4 kJ |
| 500 kcal | 2092 kJ |
| 1000 kcal | 4184 kJ |
All values in this table are mathematically exact per NIST SP 811.